1. Field of the Invention
This invention relates to a reinforcement structure effective for improving a load resisting force of a truss bridge or an arch bridge constructed over a river or on land.
2. Related Art
There has heretofore been known, as a work for reinforcing a truss bridge or an arch bridge, a method in which a structural frame(s) of a truss girder or an arch girder, which constitutes the truss bridge or arch bridge, (more specifically, an upper chord, a lower chord and a diagonal member in the truss girder or a lower chord and a vertical member in the arch girder), are abutted and overlaid by a short reinforcement member and bolted together, so that a sectional area of each structural frame is increased to thereby enhance a load resisting force.
However, the above-mentioned reinforcement work requires such troublesome work that many reinforcement plates are needed and each sheet must be bolted. In addition, a long period of time is required for the work and working costs are increased.
Moreover, many bolt heads are projected from a joined part of the structural frame through a gusset plate. When the reinforcement plates are overlaid on an area of the structural frame which excludes this joined part, a problem arises in which a load resisting force is hardly enhanced at the joined part on which a dead load and an active load are concentrated.
In order to avoid this problem, large-scale work is required in which many bolts and gusset plates are removed from the joined part and replaced with a reinforcement plate and then bolted again.